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6.11
Pressure switch adjustment
6.11.1 Air pressure switch - check CO
Adjust the air pressure switch after performing all other burner
adjustments with the air pressure switch set to the start of the
scale (Fig. 38).
With the burner working at MIN output, insert a combustion
analyser in the stack, slowly close the suction inlet of the fan (for
example, with a piece of cardboard) until the CO value does not
exceed 100 ppm.
Slowly turn the appropriate knob clockwise until the burner goes
into lockout.
Check the indication of the arrow pointing upwards on the gradu-
ated scale.
Turn the knob clockwise again, until the value shown on the grad-
uated scale corresponds with the arrow pointing downwards, and
so recovering the hysteresis of the pressure switch (shown by the
white mark on a blue background, between the two arrows). Now
check the correct start-up of the burner.
If the burner locks out again, turn the knob anticlockwise a little
bit more.
6.11.2 Maximum gas pressure switch
Adjust the maximum gas pressure switch after having performed
all the other burner adjustments with the maximum gas pressure
switch set at the end of the scale (Fig. 39).
With the burner operating at maximum output, lower the adjust-
ment pressure by slowly turning the relative knob anticlockwise
until the burner locks out.
Now turn the knob clockwise by 0.2 kPa (2 mbar) and repeat the
start-up of the burner.
If the burner locks out again, turn the knob clockwise again by
0.1 kPa (1 mbar).
6.11.3 Minimum gas pressure switch
Adjust the minimum gas pressure switch after performing all the
other burner adjustments with the pressure switch set to the start
of the scale (Fig. 40).
With the burner operating at maximum output, increase adjust-
ment pressure by slowly turning the relative knob clockwise until
the burner stops.
Now turn the knob anticlockwise by 0.2 kPa (2 mbar) and repeat
burner start-up to ensure it is uniform.
If the burner locks out again, turn the knob anti-clockwise again
by 0.1 kPa (1 mbar).
6.11.4 PVP pressure switch kit
Adjust the pressure switch for the leak detection control (PVP kit)
(Fig. 41) according to the instructions supplied with the kit.
1 kPa = 10 mbar
WARNING
20170641
Start-up, calibration and operation of the burner
36
GB
D3854
D3856
D3855
D3855
Fig. 38
Fig. 39
Fig. 40
Fig. 41
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